Variations in Boundary Layer Stability Across Antarctica: A Comparison Between Coastal and Interior Sites

• Main Authors: Dice, Mckenzie June, Cassano, John, Jozef, Gina Clara, Seefeldt, Mark
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Arctic; Antarctic; The Antarctic; Neumayer; South Pole; Antarc*; Antarctica; South pole
• Online Access: https://doi.org/10.5194/egusphere-2023-1673; https://noa.gwlb.de/receive/cop_mods_00068090; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066524/egusphere-2023-1673.pdf; https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1673/egusphere-2023-1673.pdf

The range of boundary layer stability profiles, from the surface to 500 m above ground level, present in radiosonde observations from two continental interior (South Pole and Dome Concordia) and three coastal (McMurdo, Georg von Neumayer III, and Syowa) Antarctic sites, is examined using the self-organizing maps (SOMs) neural network algorithm. A wide range of potential temperature profiles is revealed, from shallow boundary layers with strong near-surface stability to deeper boundary layers with weaker or near-neutral stability, as well as profiles with weaker near-surface stability and enhanced stability aloft, above the boundary layer. Boundary layer regimes were defined based on the range of profiles revealed by the SOM analysis. Twenty boundary layer regimes were identified to account for differences in stability near the surface as well as above the boundary layer. Strong, very strong, or extremely strong stability, with vertical potential temperature gradients of 5 to in excess of 30 K (100 m)-1, occurred more than 80 % of the time at South Pole and Dome Concordia in the winter. Weaker stability was found in the winter at the coastal sites, with moderate and strong stability (vertical potential temperature gradients of 1.75 to 15 K (100 m)-1) occurring 70 % to 85 % of the time. Even in the summer, moderate and strong stability is found across all five sites, either immediately near the surface or aloft, just above the boundary layer. While the mean boundary layer height at the continental interior sites was found to be approximately 50 m, the mean boundary layer height at the costal sites was deeper, around 110 m. Further, a commonly described two stability regime system in the Arctic associated with clear or cloudy conditions was applied to the 20 boundary layer regimes identified in this study to understand if the two-regime behavior is also observed in the Antarctic. It was found that moderate and strong stability occur more often with clear than cloudy sky conditions, but weaker stability regimes ...